The present invention relates to a hard disk drive used as an auxiliary memory device in a computer, and more particularly, to a magnetic latching apparatus for an actuator of the hard disk drive for maintaining the actuator of the hard disk drive in a parking zone while the actuator is not in operation.
Generally, the hard disk drive used as the auxiliary memory device in the computer includes a disk which is rotated at a high speed by spindle motor, and an actuator which rotates in response to a voice coil motor about a pivot point for moving a magnetic head that writes data onto tracks of the disk and reads data recorded on tracks of the disk. The magnetic head is located on a leading end of a head gimbals, which moves along both sides of the disk, wherein the magnetic head is influenced by an airflow generated on a surface of the disk as the disk rotates at a high speed to maintain a minute air gap between the magnetic head and the disk.
When the hard disk drive stops or powers off during the above-mentioned operation, the actuator is installed to move the magnetic head into a parking zone located on an inner or an outer portion in the tracks of the disk. Upon the power-off of the hard disk drive, the actuator is adjusted to move the magnetic heads into the parking zone on the disk by a residual inertia of a spindle motor. This is designed to prevent the data recorded on the disk from being damaged due to undesired contact of the magnetic head against the surface of the disk.
For stably fixing or latching a rear end of the actuator during the above operation, a method such as a solenoid, a separate voice coil motor or a magnetic latch has been employed. Among these methods, the magnetic latch is generally used. In this case, a metal plate easily attached to a magnet has to be installed to the rear end of the actuator, since the rear end of the actuator is of an aluminum material, or has a structure to which a coil is attached. Generally, in the case where the structure having the metal plate is used, the metal plate can be attached to the rear end of the actuator by using an adhesive material. However, when the adhesive material is used within the hard disk drive, there are disadvantages that a gas generated during the time it takes the adhesive material to solidify and a dust generated due to a change of an element of the adhesive material over time have a bad effect on the reliability of the hard disk drive.
A conventional electric fixing method, that uses the solenoid or the separate voice coil motor, requires an additional device for controlling these means. But, this results in another problem that the cost of product is accordingly risen due to a high price of the device.
U.S. Pat. No. 5,189,576 entitled ROTARY INERTIAL LATCH FOR DISK DRIVE ACTUATOR to James H. Morehouse, et al. discloses a mechanical latch responsive to an inertial force of the actuator for moving a latch pin to engage a finger extending from the actuator for maintaining the actuator in its proper position when the disk drive is not in operation.
In the case of using the conventional magnetic latch, there are disadvantages that since a complicated device using a damper or a spring to buffer impact generated upon the parking of head is used, the cost of product is accordingly risen, and difficulties of assembly and repair are caused.
John B. Blanks discloses in U.S. Pat. No. 5,231,556 a SELF-HOLDING LATCH ASSEMBLY comprising a magnetic latch assembly mounted on a magnet coil assembly that rotates about a pivot pin to confine a latch pin, which extends from the side of an actuator by a latch pin arm, between a latch arm of the magnetic latch assembly and a travel stop, thereby locking the actuator in a parking zone.
U.S. Pat. No. 5,224,000 entitled CRASH STOP AND MAGNETIC LATCH FOR A VOICE COIL ACTUATOR by Shawn E. Casey, et al. discloses a magnetic latch for holding an actuator in a "home" (park) position, wherein the magnetic latch comprises a pair of magnetic "L" shaped slidable poles disposed on opposite sides of a magnet, wherein the poles are of a greater length than the magnet so that a steel strike plate attached to the actuator contacts the poles to prevent the strike plate from hitting the magnet. The magnetic latch is slidably mounted in a recess of a bumper pad disposed within a frame of a bumper stop mounted on the lower casing of the housing such that the poles extend beyond a contact surface of the bumper pad.
U.S. Pat. No. 5,023,736 entitled MAGNETIC LATCH FOR DISK DRIVE ACTUATOR by Gary Kelsic, et al. discloses a magnetic latch having a pair of spaced apart parallel poles extending from a magnet for latching onto a latch plate extending from a disk drive actuator for maintaining the actuator in a "crash stop" (park) position when desired. The magnetic latch is housed in a cavity of a molded plastic housing attached to the disk drive housing.
Kai C. K. Sun, et al. discloses in U.S. Pat. No. 5,003,422 a MAGNETIC LOCKING MECHANISM, i.e., a magnetic latch, having a resilient mechanism connected to a support structure for dampening the impact of the actuator as an actuator pin extending from the actuator strikes a swing plate of the resilient mechanism. Movement of the swing plate causes the top of the swing plate to move against the resistance of a spring in response to the bottom of the swing plate being struck by the actuator. A magnet attached to the bottom of the swing plate latches onto an actuator pin extending from the actuator when the actuator is placed in park.